Unless otherwise stated, all directional indications, such as axial, radial and circumferential direction, relate to the longitudinal axis of the housing. In the case of the turbo fluid energy machine, the longitudinal axis is substantially coincident with the axis of rotation of a rotor carrying the individual impellers. An offset of the axis of rotation and of the longitudinal axis of the housing in a turbo fluid energy machine is generally a result of the alignment of the two components in relation to one another.
Such housings are already known from the patent specification DE 10 2012 223 462 B3.
A spiral groove ring corresponding to the annular insert in the preamble of the main claim is already known from DE 42 25 687 A1.
JP 5500 7914 discloses an arrangement with a multistage centrifugal compressor, in which it is provided that liquid accumulating in the return stages can be blown out as and when required by means of injected natural gas. This corresponding blow-out line is led through an end-face cover into an inner housing ring and continued there, seals being provided for the purpose of sealing this routing of the line between the inner housing ring and the cover.
EP 08400016 A2 discloses a turbo machine in which the inflow and outflow are sealed with respect to one another by means of a seal extending in the circumferential direction between an inner housing and an outer housing and end-face opening closures are likewise sealed with respect to the housing by means of static seals. The corresponding inflow and outflow chambers are filled as planned with the process fluid and are not monitored for a leakage.
DE 4011476 A1 discloses a barrel housing pump that has a seal in relation to an end-face cover.
DE 102012223462 B3 is concerned with an arrangement according to the preamble of the invention. A sealing arrangement with a monitored intermediate chamber is provided here between two seals, the two seals being arranged between the housing and an end-face cover. The arrangement is radially encompassing and must be formed such that the radial installation space of the housing wall thickness is not exceeded by the sealing arrangement.
In particular in the area of radial turbo compressors and radial turbo expanders, the use of such housings is customary.
In the context of this patent application, the term “housing casing” means a preferably substantially cylindrical form of housing along a longitudinal axis, which on at least one axial side has a releasably fastened cover and on the other side is either of a closed form—that is to say is in one piece with a closable end-face cover—or likewise has a releasably fastened cover on the axial end face. In particular, the housing has on at least one axial end-face side a lead-through for a shaft, which transfers torques to or from the rotor of a fluid energy machine in relation to the housing according to the invention. This shaft generally has an axis of rotation that coincides substantially with the longitudinal axis of the housing. An application of the invention is in the area of radial fluid energy machines, though an application in the area of axial fluid energy machines is also conceivable in principle.
The invention is specifically concerned with the static sealing of the housing cover in relation to the housing casing by using an additional annular insert. In particular when the compression or expansion of toxic or explosive or in some other way hazardous fluids is involved, reliable sealing of the cover in relation to the housing casing is operationally necessary for reasons of safety.
To register any failure of the seal between the housing casing and the cover, it is known to provide between an interior of the housing with a potentially hazardous process fluid and the surroundings an intermediate space that is monitored for any escape of the process gas in series arrangement z of at least one seal that seals the cover. Advantageously, this intermediate space is also sealed with respect to the surroundings, so that, in the event of the inner seal being defective, no potentially hazardous process gas can escape into the surroundings and monitoring of the intermediate space indicates the necessity for the inner seal to be exchanged.
It is already known from the aforementioned DE 10 2012 223 462 B3 to save radial installation space by providing in addition to a radial offset between an inner seal, which seals the intermediate space in relation to the interior of the machine, and an outer seal, which seals the intermediate space that is monitored in relation to the surroundings, also an axial offset. As a result, the intermediate space is sufficiently large while having a small radial extent, in that the required size of the intermediate space is not only achieved by radial installation space, but also the possibility of axial installation space is utilized.
Nevertheless, the known sealing arrangement requires more radial installation space than is desired.